Question: $ 81^{-\frac{1}{2}}$
Explanation: $= \left(\dfrac{1}{81}\right)^{\frac{1}{2}}$ To simplify $\left(\dfrac{1}{81}\right)^{\frac{1}{2}}$ , figure out what goes in the blank: $\left(? \right)^{2}=\dfrac{1}{81}$ To simplify $\left(\dfrac{1}{81}\right)^{\frac{1}{2}}$ , figure out what goes in the blank: $\left({\dfrac{1}{9}}\right)^{2}=\dfrac{1}{81}$ so $ \left(\dfrac{1}{81}\right)^{\frac{1}{2}}=\dfrac{1}{9}$